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Chapter 8 Practice Paper: Practical Electricity — question paper

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Secondary 4 · Physics (G2 / G3)

Chapter 8 Practice Paper

Practical Electricity

Duration: 40 minutes
Total: 30 marks
Name:
Class:
Register No.:
Date:

READ THESE INSTRUCTIONS FIRST

  • Write your name, class and register number in the spaces at the top of this page.
  • Answer all questions.
  • Give numerical answers correct to 3 significant figures unless stated otherwise, with units where a quantity is calculated.
  • The number of marks is given in brackets [ ] at the end of each question or part question.
  • The total number of marks for this paper is 30.

Original practice material written for the MOE Physics syllabus. It is not an official MOE or school examination paper. Heating effect of current, P = VI and E = VIt, kilowatt-hour and running costs, mains wiring (live, neutral, earth), fuses and circuit breakers, switches on the live wire, earthing and double insulation, common household hazards.

For Examiner’s Use
Section A/ 10
Section B/ 20
Total/ 30

Section A: Multiple-choice questions[10 marks]

Choose the one correct answer for each question.

  1. 1

    A heater draws 9.0 A from a 230 V supply. The power it converts is about

    1. A26 W
    2. B2070 W
    3. C39 W
    4. D20700 W
    ( )
  2. 2

    One kilowatt-hour is the energy used by a 1.0 kW appliance running for

    1. A1 second
    2. B1 minute
    3. C1 hour
    4. D1000 hours
    ( )
  3. 3

    The wire in a mains plug that is coloured green-and-yellow is the

    1. Aearth wire
    2. Blive wire
    3. Cneutral wire
    4. Dfuse wire
    ( )
  4. 4

    A switch controlling a lamp must be wired in the live wire because this

    1. Akeeps the lamp at 0 V when switched off, so it cannot shock anyone
    2. Blets the lamp last longer
    3. Cincreases the lamp’s brightness
    4. Dreduces the current used
    ( )
  5. 5

    A 2300 W kettle on a 230 V supply needs a fuse rated

    1. A3 A
    2. B5 A
    3. C13 A
    4. D100 A
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

  1. 1

    An electric iron is rated 1800 W, 230 V and is used for 45 minutes.

    1. (a)

      Determine the current the iron draws.

      current =A[2]
    2. (b)

      Calculate the energy it converts, in kilowatt-hours.

      energy =kW h[2]
    3. (c)

      Electricity costs 30 cents per kW h. Calculate the cost of this use.

      cost =cents[2]
  2. 2

    A student inspects a mains plug and finds the blue wire connected to the fuse terminal, the brown wire connected to the earth terminal, and no wire at all on the terminal marked with green-and-yellow stripes.

    1. (a)

      Identify the brown and blue wires by name and function.

      [2]
    2. (b)

      State the two wiring errors and the danger each creates.

      [3]
    3. (c)

      State the correct wiring in one sentence.

      [2]
  3. 3

    A metal-bodied washing machine is protected by an earth wire and a 13 A fuse. A fault makes the live wire touch the metal casing.

    1. (a)

      Explain why a person touching the faulty machine is safe while the earth wire is intact.

      [3]
    2. (b)

      Explain why the fault is dangerous if the earth wire is broken.

      [2]
    3. (c)

      State one advantage of a circuit breaker over a fuse.

      [2]

— End of paper —